Rover headbolt threads

[Des]

I've bought these sexy studs, they look lovely and have a hex socket to screw them in, they're way too good for a manky RV8.

 

 

And now I want to drill and tap where Rover didn't, only snag is that they appear to be 7/16 UNC with a 14 TPI, local hardware place Simbles, been there for ever and do know their stuff, only have taps with a TPI of 13, and seem to think the one I need is a bit of an oddball. Where can I get an oddball tap from?

[Des]

I've bought these sexy studs, they look lovely and have a hex socket to screw them in, they're way too good for a manky RV8.

 

 

And now I want to drill and tap where Rover didn't, only snag is that they appear to be 7/16 UNC with a 14 TPI, local hardware place Simbles, been there for ever and do know their stuff, only have taps with a TPI of 13, and seem to think the one I need is a bit of an oddball. Where can I get an oddball tap from?

[pandamonium]

I'm no expert, but will ask an engineer friend at work who has a large collection of old taps if he has one like this.

[pandamonium]

I'm no expert, but will ask an engineer friend at work who has a large collection of old taps if he has one like this.

[OwdChina]

Ahh, unified coarse. Should have those at work somewhere. I'll have a gander tonight. (night shift)

[OwdChina]

Ahh, unified coarse. Should have those at work somewhere. I'll have a gander tonight. (night shift)

[pandamonium]

Spoke to an engineering place i use, can get you a brand new delivered one on wed next week for 18ish plus vat.

[pandamonium]

Spoke to an engineering place i use, can get you a brand new delivered one on wed next week for 18ish plus vat.

[OwdChina]

hey Dez....those studs look to have different threads on the ends of each stud. One fine, one coarse. Which studs are you replacing coz they look different lenghs also. Remember, if your drilling blind holes you may need a taper and a bottom tap,,, depending on metal type.

 

Edited; head studs, must pay attention.

Edit again; Replacing 12mm with 7/16 ?????????? Erm..NO.....???

[OwdChina]

hey Dez....those studs look to have different threads on the ends of each stud. One fine, one coarse. Which studs are you replacing coz they look different lenghs also. Remember, if your drilling blind holes you may need a taper and a bottom tap,,, depending on metal type.

 

Edited; head studs, must pay attention.

Edit again; Replacing 12mm with 7/16 ?????????? Erm..NO.....???

[Bobthebeard]

hey Dez....those studs look to have different threads on the ends of each stud. One fine, one coarse. Which studs are you replacing coz they look different lenghs also. Remember, if your drilling blind holes you may need a taper and a bottom tap,,, depending on metal type.

 

Edited; head studs, must pay attention.

Edit again; Replacing 12mm with 7/16 ?????????? Erm..NO.....???

 

Lol!

I think you REALLY must have married my ex wife...! Your mind is going.. Lol!

[Bobthebeard]

hey Dez....those studs look to have different threads on the ends of each stud. One fine, one coarse. Which studs are you replacing coz they look different lenghs also. Remember, if your drilling blind holes you may need a taper and a bottom tap,,, depending on metal type.

 

Edited; head studs, must pay attention.

Edit again; Replacing 12mm with 7/16 ?????????? Erm..NO.....???

 

Lol!

I think you REALLY must have married my ex wife...! Your mind is going.. Lol!

[OwdChina]

Yeah i think it is sometimes....thing is 12mm is bigger than 7/16 so the holes are already to big.....just wondering what des's doin.

 

Was she blond.....and smell of fish an chips .

[OwdChina]

Yeah i think it is sometimes....thing is 12mm is bigger than 7/16 so the holes are already to big.....just wondering what des's doin.

 

Was she blond.....and smell of fish an chips .

[gearoil]

7/16 UNC 14TPI - Cromwell tools.

 

Order codes:

 

Taper - SHR-085-0880A

 

Second - SHR-085-0880B

 

Plug - SHR-085-0880C

[gearoil]

7/16 UNC 14TPI - Cromwell tools.

 

Order codes:

 

Taper - SHR-085-0880A

 

Second - SHR-085-0880B

 

Plug - SHR-085-0880C

[OwdChina]

OK Des, i have brand new (made in China) taper and plug taps in my hand. It's a common size in USA. 7/16 by 14pitch NC.

PM me an address and i'll send em over the pond fer ya.

[Albert Ross]

That would figure, as it was originally a US built Buick 215.....

[Des]

Completely forgot I posted this, thanks for the help all, that's an uncommonly kind offer meowdchina, but I don't want to put you to the expense of sending as it seems I can get the taps from Cromwell Tools, thanks for the pointer gearoil, just been carried away for hours on their website.

Going to have some drilling fun as I have both block and heads missing their holes, have early heads which I can use as a guide so should be easy enough. The correct procedure with these engines is to have thicker liners put in, with a better sealing surface, but at a cost of around £1400 totally unviable, that kind of money would go a long way to making a better engine fit in, maybe something with another cam or more valves.

[Des]

Found a company called Tracytools in Devon and ordered taps from their website, arrived very quickly, £3 per tap. Progress is slow but had a couple of hours spare today and came up with an idea of drilling accurately, was thinking of sitting / clamping a pedestal drill to the block, instead, grabbed the old type fully drilled head I have, measured the bolt holes then turned a couple of bars to be a snug fit, bored one 5mm to guide a pilot bit and the other 9.2mm to guide the bit for the hole I want to wind a tap into.

 

 

I iz toolmaker.